The present invention relates to an electrical power distribution system for a fuel cell vehicle.
One type of fuel cell vehicle of the past was a hybrid fuel cell vehicle having a fuel cell system with a fuel-reformer and a battery.
In a fuel cell vehicle of this type, the fuel-reformer is usually formed by a fuel reformer and a combustor, reformed gas from the fuel reformer and air from a compressor being used by the fuel cell to generate electrical power, excessively generated electrical power and regeneratively generated electrical power from the motor being stored in the battery. In this system, in response to operation of the acceleration pedal by the driver, electrical power is distributed from the fuel cell and the battery to the motor, the fuel reformer, the combustor, and the compressor, for example, via an electrical power adjuster.
In the above case, when the driver sets the ignition key to on to start up the fuel cell vehicle, because reformed gas is not generated for a period of several minutes to several tens of minutes after the fuel reformer is started, it is not possible for the fuel cell to generate electrical power. Therefore, the power for the motor is taken from the battery.
Thereafter, at the point at which the fuel reformer starts to generate a standard amount of reformed gas that is usable in the fuel cell, electrical generation is started. Because the temperature of the fuel cell has not yet increased at this point, however, it is not possible to generate the rated amount of electrical power.
Subsequently, as electrical power generation continues, heat generated internally in the fuel cell causes a rise in temperature, making it possible to generate the rated amount of electrical power.
In a fuel cell vehicle system of the past, however, a large amount of electrical power was required to start the fuel reformer and reform fuel.
More specifically, in order to start the fuel reformer and reform fuel, because the heat generated by the combustor is re-used in vaporizing the fuel and absorbed in the fuel reforming reaction, there is a need to start the combustor as well. To start the fuel reformer that performs a chemical reaction, it is necessary to reach a prescribed temperature, for example approximately 300xc2x0 C. in the case of steam reforming, thereby requiring a large amount of energy, which is difficult to supply from only a battery.
For this reason, the thermal energy generated when the methanol fuel is combusted is used to raise the temperature of the fuel reformer. When this is done, however, the catalyst experiences meltdown at the high temperatures that occur. Given this situation, in order to achieve combustion at an appropriately high temperature, it is necessary to supply a large amount of air using a compressor, thereby increasing the amount of electrical power required.
In vaporizing the methanol, it is necessary at the startup stage to use an electrical vaporizer, and because of the large latent heat of methanol, the amount of electrical power required for this is large. Additionally, an electrical heater (catalyst heater) is required to bring the temperature to the minimum temperature for ignition of the catalyst, and this also requires a large amount of electrical power.
Thus, the amount of electrical power required for starting a fuel reforming system is extremely large, this being approximately equivalent to the amount of electrical power consumed in operating the fuel cell vehicle over a flat terrain at a high speed. Under these conditions, if the electrical power and capacity of the battery is sufficient to cover the added amount of electrical power required to start up the fuel cell system in addition to the standard amount of energy required for operating the electrical vehicle, during the period until it becomes possible to generate the standard amount of reformed gas usable in the fuel cell, it is possible to supply sufficient power from the battery.
However, a situation can be envisioned in which it is not possible for space and cost considerations to mount in the vehicle both fuel cell system including a fuel reforming system and such a large-capacity battery. Thus, limitation of the battery container size is inevitable, thereby making it difficult to supply sufficient electrical power to run the motor before it is possible to generate the standard amount of reformed gas for use in the fuel cell.
Thus, in a fuel cell vehicle system of the past, in the period of several minutes to several tens of minutes up until the point at which it is possible for the fuel reforming system to generate sufficient reformed gas for use by the fuel cell, a large amount of electrical power is required to start the fuel reforming system, and hence the fuel cell system as a whole. This made it impossible to obtain sufficient electrical power from the battery to run the motor, making it impossible to achieve sufficient running performance.
Accordingly, in view of the above-described problems with the related art, it is an object of the present invention to provide an electrical power distribution system for a fuel cell vehicle capable of achieving sufficient running performance during startup of the fuel reforming system.
An aspect of the present invention to achieve the object is an electrical power distribution system for a fuel cell vehicle, comprising a fuel reformer generating reformed gas from fuel, an air supply source supplying air, a fuel cell generating electrical power from the reformed gas and the air, a battery storing electrical power generated by the fuel cell and discharging electrical power, and an electrical motor providing drive to the vehicle by electrical power supplied from the fuel cell and the battery, wherein the electrical power distribution system is operative in response to operation of an accelerator for distribution of electrical power from the fuel cell and the battery to the fuel reformer, the air supply source, and the motor, and further comprises an operation detector detecting a kick-down operation of an accelerator pedal, and a controller which in the case of a kick-down operation being detected during startup of the fuel reforming system, including the fuel reformer and the air supply source, performs control so as to limit the electrical power required for startup of the fuel reforming system and increase the amount of electrical power distributed to the motor.
In this aspect the present invention, by detecting the kick-down operation of the accelerator pedal, it is possible to limit the electrical power required for starting and increase the power distributed to the motor, thereby giving priority to the motor, and achieving sufficient running performance during the startup of the fuel reforming system.